1. Field of the Invention
The present invention relates to an antenna for AM/FM radio broadcast bands and television broadcast bands disposed on the upper remaining part above heating conductor wires of a defogger mounted on the rear window of automobiles.
2. Background Art
Hitherto, in the case where a glass antenna is mounted on a window of vehicles, the antenna mounted on the rear window is generally adopted because it blocks a driver's view when it is mounted on the front window on the driver side.
Many applications have been filed in the past regarding the glass antenna for the AM radio broadcast waves/FM radio broadcast waves and the TV broadcast waves. The upper remaining part above the heating conductor wires on the rear window has relatively large space for mounting a glass antenna, and the receive gain can be increased as the position to mount the antenna is higher. Therefore, the glass antenna is mounted on the upper remaining part in the most cases, and there are many antennas commercially available.
On the other hand, a defogger, in which current is carried between bus bars connected to both ends of a plurality of heating conductor wires disposed nearly horizontally by a direct-current power supply and the conductor wires disposed nearly horizontally are heated to defog a window, is also used as an antenna in many cases in addition to functioning it as a defogger.
The defogger like this is often used as an antenna. The defogger is disposed with conductor wires arranged nearly vertically and orthogonal to the heating conductor wires formed of a plurality of nearly horizontal wires and they are connected to an antenna terminal directly through leads from the heating conductor wires or bus bars of the defogger. Alternatively, a part of the horizontal wires of an antenna element mounted on the upper remaining part above the defogger is brought close to the heating conductor wire of the defogger and capacitive-coupled thereto.
For example, JP-A-9-69713 discloses a glass antenna for automobile windows including: a feeding terminal formed on the surface of a window; an antenna device conductor; a connection line for outputting reception signals of the antenna device conductor to the feeding terminal on the corner part of the window or the side part of the window; and two conductor lines, wherein one of the two conductor lines is disposed along the edge of the window, one end of this conductor line is connected to the connection line joined to the antenna device conductor, and the other end is an open end, and the other of the two conductor line is disposed along the conductor line, one end of this conductor line is connected to the feeding terminal, and the other end is an open end.
Furthermore, JP-A-8-84011 discloses a glass antenna having defoggers and antenna conductors extended on the glass, the glass antenna including: a feeding point disposed above or below the defoggers; first antenna conductor elements in a closed loop form fed from the feeding point and extended along the glass surface; and a second antenna conductor vertically extended along the glass surface in the area where the defogger is extended and a part thereof directly connected to a part of a hot wire of the defogger, wherein the first antenna conductor elements are disposed with respect to the defoggers so that the hot wire connected a part of the second antenna conductor element is capacitive-coupled to a part of the first antenna conductor element.